In recent years, quick couplers have become commonly used for detachably connecting buckets or other tools to earth working machines, such as backhoes, excavators and loaders. Such quick couplers are advantageous because they allow a machine operator to quickly change from one bucket to another. Of course, the operator can detach and attach other work tools, as well as buckets, for performing other types of work. Thus, the use of a quick coupler makes the machine much more efficient and versatile.
Several different types of quick couplers have been employed in the past. One of such quick couplers is disclosed in U.S. Pat. No. 5,494,396 for a Coupling Device for a Work Implement, issued to Timothy D. Geier et. al. on Feb. 27, 1996. Such coupling device utilizes a manually actuated latching arrangement that requires the operator to wrench out the latching member on the coupling device. Other types of quick couplers are provided with a hydraulically actuated latching mechanism to allow the operator to detach and attach such tools from the cab. One of such quick couplers with a hydraulically actuated latching mechanism is disclosed in U.S. Pat. No. 5,147,173 for a Coupling Device, issued to Raymond L. Fauber on Sep. 15, 1992. In such coupling device, a double acting hydraulic cylinder is employed to both engage and disengage the coupler from the tool. This coupling device also employs a coil spring as a back-up force to the latching wedge in the event hydraulic pressure is lost. Another such quick coupler arrangement is disclosed in U.S. Pat. No. 5,634,736 for a Quick-Disconnect Coupling Device, issued to Eric A. Brown et. al. on Jun. 3. 1997. In this coupling device, a double acting cylinder actuates an over center linkage arrangement to operate the latch. However, no back-up force is provided in the event of the loss of hydraulic pressure.
While prior quick couplers satisfactorily perform their intended task, some are inconvenient because they require the operator to leave the cab to operate them. Others employ double acting cylinders that require two hydraulic lines or are otherwise complex and costly. Others do not employ a back-up system in the event of a loss of the primary latching force.
The present invention is directed at overcoming one or more of the problems set forth above.